In the past there have been various proposals for blind fasteners including separately drivable inner and outer fastener components, such as shown in U.S. Pat. Nos. 1,587,317 and 3,691,924. While such fasteners can be very effective in holding two or more workpieces together, the usefulness of such fasteners is sometimes limited since it is not usually possible to provide for powered driving of the fasteners into place since two separate impacting forces must be applied to the separate fastener components. Where a powered driving means is utilized, first the outer component is driven through the workpieces, the tool removed, and then the inner component driven through the outer component to deform it into locking engagement with the workpieces, holding them together. Also, such fasteners can be difficult to construct, and relatively expensive, and are difficult to use with a wide variety of materials and numbers of sheets to be fastened together.
According to the present invention, a powered impacting device is provided that provides power driving of both the inner and outer fastener components of two piece blind fasteners without the necessity of first driving the outer component, then inserting the inner component, and then driving the inner component. Also, according to the present invention, particular two-piece fasteners and an assembly thereof are provided that result in excellent fastening of a wide variety of materials together, are inexpensive to manufacture, allow for automatic feeding thereof to the impacting device, and which may be made capable of imparting a rotational component to the fasteners during firing to ensure that the fasteners are driven in a true manner through the workpieces.
According to the powered impacting device of the present invention, a first, inner driving piston, and a second outer, driving piston--concentric with the first piston--are provided. Means may be provided for supplying actuating pressurized fluid to the second piston and then to the first piston to effect axial movement of each, in the same direction, and means are provided for receipt of a two-piece fastener--having concentric inner and outer components--in operative relationship with the pistons so that the outer component is driven by the second piston, and the inner component is driven by the first piston. The fastener receipt means includes a firing barrel, and a magazine or the like is provided for automatically feeding fasteners into the firing barrel for automatic firing thereof. The barrel may be rifled, and each fastener then includes at least one frangible plastic link associated therewith for engaging the barrel riflings to impart rotational movement to the fastener while it is being driven, but the plastic links disintegrate fully upon impaction of the fastener on a surface. A loading gate is provided for separating connectedautomatically fed fasteners from each other, and for sealing off the firing barrel from the magazine during driving of the fasteners.
So that only one valve need be provided for supplying fluid to the pistons, the second piston may be formed so that it provides a cylinder wall for guiding movement of the first piston, with biasing means disposed between the pistons for biasing the first piston to a particular relative axial position with respect to the second piston. Upon application of an impacting force to the pistons by a third piston, the first and second pistons will be driven together until the second piston drives the outer fastener component through the work and is stopped. The first piston is massive enough so that upon termination of the movement of the second piston, the first piston will continue movement, relative to the second piston, against the bias of the biasing means with sufficient force to drive the inner component of the fastener into the desired position with respect to the work. The means for receipt of the two piece fastener includes a cylinder for guiding movement of the second piston with an opening therein for receipt of the fastener.
Various safety mechanisms are provided including means for preventing a supply of actuating pressurized fluid to either of the pistons unless the end of the impacting device out of which the fasteners are fired is in contact with the surface, unless a safety handle is positively rotated against spring pressure, and unless the loading gate (where one is used) is in closed position.
According to the invention, each fastener outer component comprises a generally tubular member having at least two grooves extending along the body so that two distinct tip portions are provided, forming a penetrating point thereof, and cam engaging interior portions. The grooves extend a sufficient distance along the body of the outer member so that the outer component will penetrate the desired thickness of material to be fastened together without splitting, but so the tip portions may be moved radially outwardly by the inner component a sufficient distance to effect fastening of the material together. The outer component also includes a head portion at the opposite end thereof as the tip. Each inner component comprises a cylindrical member having a pointed tip portion, and cam surface means for engaging the cam engaging interior portions of a cooperating outer component for camming the distinct tip portions of the outer component radially outwardly into fastening engagement with the workpieces. An assembly of two-piece fasteners may be provided, which fasteners are operatively connected together for automatic feeding thereof by frangible connector means. At least one frangible plastic link also may be associated with each fastener for engaging bore riflings in a firing barrel for the fasteners to thereby impart rotation to at least one component of each fastener during firing.
It is the primary object of the present invention to provide a system for the ready fastening of a least two workpieces together with practiced, inexpensive two-piece fasteners. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.